controller, relay or...

[jdcburg]

I ripped the 2x8 down to 6 inches (the width of the batteries) and screwed some sheet aluminum on the sides so it's narrower and a little lighter. I've attached a picture. Does anybody know if SLAs can rest on their sides or ends? I'm not just worried about leaking but cracking the case or knocking the plates loose during the normal bumps of riding. Sometime I might try to build an "L" rack attached to the front or rear tube. I would like to graduate to solid cells sometime when (if) the price comes down.

ps the extra wires and alligator clips are the jumpers I use when charging - jd

 

[deacon]

That is why they are called sealed, you can set them upside down if you want. Worry about things rubbing against the cases to rub holes from the vibrations otherwise you should be good to go. I always have bolt heads near them so I line anything I build with cardboard from a heavy box.

When mind fail, and they do, it is at the terminals. They tend to break off now and then or develop leaks there. At least for me but then I'm pretty rough on them.

 

[starrunner]

jdcburg, I really like your project and am considering doing a similar one. I do have an old 3 speed English racer bike that I might could use the wheel from. It has been out in the weather many years, so I don't know yet. I have a question. What do you think your results would have been if you had used a motor without that gear reduction? Any guess? I would like to get better results on hills than you got. One thing I can think of is to put a bigger sprocket on the 3 speed wheel hub, but I know that would complicate matters figuring out how to attach it and get it centered properly. And do you think you might have gotten better results if using a controller?

 

[starrunner]

I have a couple more questions. Is this the motor you used? And I searched high and low on escooterparts for that $23 sprocket you used and can't find it. That sure is high for a small sprocket. Can you point me to the one you used? And what do you look for when you're looking for bike chain sprockets? Is it 8mm? It's easy to get all screwed up with the metric measurements. I know what #25, #35, #40, #41 etc chain and sprockets are when I see them (the ANSI system) listed but as far as bike chain size, it's #40, but the scooter parts sites don't list it this way.

 

[deacon]

try these folks for your parts... Not sure what all they have but they have a lot of scooter stuff I adapt to bike use. TNC Scooters (Scooter Sales and Service)

 

[jdcburg]

Starrunner - Yes, the Dirt Quad motor you found is the one I used. The gear reduction is what gives it the power for hills. Otherwise you would have to use a very large sprocket. There is a more powerful gear reduction Unite motor (MY1018Z - 450 watts) that comes with a bicycle sprocket already attached. As Deacon mentioned TNC TNC Scooters (Scooter Sales and Service) is a good place to shop for stuff. They have it for $60 here That's a pretty good deal when you consider everything - more power, shipping from 2 places, etc.

The sprocket is a bicycle chain sprocket, Item # SPR-B119 from Electric Scooter Sprockets - ElectricScooterParts.com I found them very good to deal with but you're right this item is more expensive than most other sprockets. I couldn't get any info from Razor about the shaft size or sprocket before I bought the motor and this was the only bike chain sprocket I could find that would fit the shaft. Even then, I had to shim it out with a couple of washers with notches filed in them. I found #40 chain to be the right pitch (1/2" between links) but too wide. 1/2"x1/8" bicycle chain (BMX chain) is widely available, inexpensive, and works perfectly.

The relay and momentary switch were a good deal - $10 for both - but I quickly found out the downside. I was stopped and leaned over the handlebars to check something and accidently hit the switch. The chain broke instantly and wrapped itself around the sprocket as I walked it to the curb, locking up the front wheel. That is the danger of any fwd bike - if something breaks and locks up the front wheek at speed, your head will be the first thing to hit the ground as it all comes over on you. I think if it had broken while turning, centrifugal force would have spun it outward and free of everything, but there is no way to guarantee that. I think the most chain stress is when I first start the motor, which is usually going uphill at fairly slow speeds, and I try to start it while I'm moving fast enough so there is no "jerk" when it starts. I will probably get a thumb throttle and controller sometime soon to make it less likely to stress everything.

Keep me posted and feel free to ask any other questions - jd

 

[deacon]

The beauty of friction drive is if it locks up, it just slows you down.

 

[starrunner]

Thanks a lot for the info, jd. That motor is out of stock at tnc, but when I saw the pic of it, I saw that it appears to be the exact same motor on a Currie ezip bike. So, when I get ready to buy one from whoever might have it in stock, I can just look for that type motor since it will usually have a bike sprocket already on it ready to go. TNC even has the motor mount and controller for it.
The first thing I thought of when seeing you guys using the instant on method was all that torque being applied at once. It's no surprise at all that the chain broke. That's why I plan to use a controller if at all possible. Even if you get a pedal start then turn on the switch, it still puts at least some stress on the chain and hub. But on the upside, this didn't happen during your normal testing of the bike and only happened when you accidentally hit the switch. Hopefully it didn't break the hub.

 

[starrunner]

jd, I'm also curious about this. Does your motor have a loud "whir" to it or is it basically silent? The other motor we referred to that appears to be just like the Currie ezip motor definitely has a loud whir and is far from silent. I can't see anything but the sprocket side of your motor but assume it's the motor with the black, longer body than the flatter Currie type. I believe it's only the brushed motors that are loud.

 

[jdcburg]

Yes the motor itself makes a little whirring noise. Under load, the gear reduction unit makes a kind of high pitched noise, like an electric drill. That's quite a bit louder than the motor itself. Usually when I hit the switch I am going faster than the motor will drive it but as the hill gets steeper I slow down and I can hear the motor take hold. I've ridden several times since the chain break and everything seems to be working fine. But I ordered a controller and throttle from TNC today. We'll see how things work with that - jd

 

[deacon]

My motor also make a whine sound very high pitched. It is more noticeable at lower speeds for sure.

I actually prefer the on off switch but I use all controllers now because the motor will throw a chain even a small one when started at full speed under a heavy load. Load being my fat butt from a standing start. On a pedal start it didn't seem to do that. The other good thing with the controller is that it allows the motor to help me start on a hill.

 

[jdcburg]

Well, I fried my first controller, a CT-201C6 from TNC. I was hooking it up the first time. I plugged in the motor to the motor plug and the 3 throttle wires to what I thought were the correct slots in the the plug labeled "timing," which I figured was Chinese for throttle. I left the brake and charger plugs open. I hooked up the battery last and it sparked. I read somewhere that the wires might spark when you first plug the controller in, but then the controller let out a hiss and it started smoking right away. The throttle was closed. The front wheel was off the ground and the motor didn't seem to be trying to turn, so I think it was just the controller shorting out. The motor needs reverse polarity to run correctly so that's how I hooked up the controller. I'm guessing that's what fried it. The controller, battery and motor are electrically isolated from the frame. So I'll go back to the relay and momentary switch until I figure out what happened. Suggestions are welcome - jd

 

[deacon]

The throttle will go to the plug called derailleur I think on most controllers. But then that is from a man who burned up two of them in two days lol. Today that is.

I went back to a straight switch on one of the bikes. It runs a lot faster that way but there is no way to do pedal assist. It is all wide open as you well know.

 

[starrunner]

That's really a bummer. Sorry to see that happen. Don't the controllers come with any decent wiring diagrams?

 

[deacon]

usually all you get is labels on the plugs... Most people buy them to replace an existing controller. The best DIY ones are a couple of heavy duty from tnc. they just have battery, motor, throttle and brake circuits. Much easier to figure out and work with.

 

[jdcburg]

The controller came with instructions, but the instructions showed a plug labeled "derailleur" and the only plug that had the same number/color wires was labeled "timing" so I figured that was it. The only other open plugs were labeled "charger" & "brake" I'm guessing I burned out some diodes reversing the polarity, but I didn't want to cut the motor wires to reverse it. Any other ideas? - jd

 

[deacon]

reversing the motor wires will only make the motor run backwards. If the polarity smoked it then it was the battery polarity. On most of my controllers the battery is black and red.. on the motor it can me several different colors. black and red, black and green, blue and white... blue and brown... everything you can imagine but like i said all it does is make the motor run backwards.

the throttle just will not work if you wire it wrong. I don't think you can damage the controller that way. I think mostly it is the power leads that smoke it. If you put it in backwards, or you put in too much current it will smoke I think.

I have no idea how to fix one once it is burned. I usually just toss mine. What is the wattage of your motor? and the voltage of your power pack...

 

[jdcburg]

It's a 350 watt 24 volt motor. The controller is rated for 24 volts/29 amps. 350/24*1.25 is 18.3 amps, well under the controller's rating. But I hadn't even done anything - it started burning the second I plugged the power in - jd

 

[deacon]

if you had it wired right it might have been a bad controller. See if the guy you bought it from will take it back. If not let me know... I have a 350 controller I'm not using. I would prefer you get yours replaced. If you can't do that, we can work a deal for the one I know worked fine when I removed it from the bike. let me know

 

[TheE]

I don't know how these controllers are built, but sometimes they'll put a diode across the voltage rails which will give it's life if the polarity is connected the wrong way. Might be worth opening up just to see.